Conventionally, as methods of collecting device-condition information of steam traps as an example of devices to be managed, methods (1) and (2) as follows are known.
(1) Direct collection method: By a contacting operation (an example of detecting operation) of a compact information collecting unit having a sensor for sensing ultrasonic oscillation and temperature on an outer surface of a steam trap (an example of a portable unit for device condition detection) with each of the number of steam traps, device-condition information of respective ones of the number of steam traps are collected one after another (see Patent Document 1 identified below).
(2) Indirect collection method: For and in correspondence with each steam trap, there is provided a stationary information collecting unit having a sensor for detecting ultrasonic oscillation and temperature of the outer surface of steam trap, the collecting unit being set in contact with the outer surface of the steam trap corresponding thereto, and via wireless communication between each one of these information collecting units and a central control apparatus, device-condition information of the number of steam traps are collected (see Patent Document 2 identified below).